This invention relates generally to a method, apparatus, and system for enabling communication between networks. More particularly, this invention relates to a method, apparatus and system and method for enabling communication between second generation and third generation packet data networks.
There are many types of public land mobile networks (PLMNs), e.g., a Global System for Mobile Communications (GSM), a Digital Cellular System for Mobile Communications (DCS 1800), and a Personal Communication System (PCS). These networks provide a wide range of services and facilities to mobile subscribers that are roaming around between individual cells of the mobile radio communication networks. These networks support circuit-switched communication.
Global Packet Radio Service (GPRS) has been developed to support packet-switched communication. GPRS is supported in second generation systems, e.g., second generation GSM systems.
A Universal Mobile Telecommunications System (UMTS) is currently being standardized within the 3rd Generation Partnership Project (3GPP), which is a cross-regional cooperative project to develop a third generation standard which can be accepted in as many regions of the world as possible. The UMTS will build on the success of the GSM system.
The UMTS will support both circuit-switched data communication and packet-switched communication. Thus, the UMTS will be useful for exchanging voice and non-voice data quickly and efficiently.
FIG. 1 illustrates an exemplary network supporting circuit-switched and packet-switched communication. In FIG. 1, a mobile station (MS) communicates with one or more Public Land Mobile Networks (PLMNs). A first network (PLMN1) is considered the Home PLMN (HPLMN) and includes a Home Location Register (HLR) containing subscriber data for subscribers to the network. The HPLMN also includes a Gateway GPRS Support Node (GGSN) for enabling packet-switched communication. PLMN2 and PLMN3 are considered visiting PLMNs. Each PLMN, other than the HPLMN, includes one or more Mobile Switching Centers (MSCs) for performing circuit switching for the mobile station and one or more Visitor Location Registers (VLRs) for storing data regarding subscribers to other networks that may be roaming in the network. The PLMNs also include Serving GPRS Support Nodes (SGSNs) for supporting packet-switched communication.
The HLR of PLMN1 communicates with VLR1, VLR2, and VLR3 for updating subscriber information, e.g., when a subscriber roams into an area served by one of these VLRs. The VLRs also communicate with each other.
The SGSNs are at the same hierarchal level in the network as the MSC/VLRs and function in a similar manner as the VLRs, but for packet-switched communication. The SGSNs keep track of the location of the GPRS user, perform security functions, and handle access control. The SGSNs communicate with the HLR to obtain subscriber profiles. The SGSNs also communicate with each other, and the SGSN of PLMN3 communicates with the base station subsystem (BSS) which, in turn, communicates with the MSC connected to VLR2 and with the MS.
The GGSN is the interconnection point for packet data between the GPRS network and the public data network. The GGSN is connected to the SGSNs via an Internet Protocol (IP) backbone. User data, e.g., from a GPRS terminal to the Internet, is sent encapsulated over the IP Backbone.
To accomplish roaming between GPRS and UMTS packet data networks, signaling between the networks and forwarding of user data are required. However, the network architectures for GPRS and UMTS networks are different, thus making interaction between the networks difficult.
In a second generation GPRS network, communication is performed node to node, as shown in FIG. 2. Second generation GPRS support nodes (2G-GSNs), e.g., GGSNs and SGSNs, communicate with each other using a GPRS tunneling protocol (GTP) described in, e.g., “GPRS Tunnelling Protocol (GTP) across the Gn and Gp Interface”, GSM 09.60 ver. 6.7.0 release 1997, Draft ETSI EN 301 347 v6.7.0 (July 2000).
In a third generation UMTS network, communication is performed in two different planes, as shown in FIG. 3. In FIG. 3, third generation GSN (3G-GSN) servers communicate with each other using a GPRS tunneling control protocol (GTP-C), and the 3G-GSN gateways also communicate with each other using a GPRS tunneling user protocol (GTP-U). The 3G-GSN gateways also communicate with the 3G-GSN servers using a gateway control protocol (GCP). The 3G-GSN gateways and servers may be GGSNs and/or SGSNs.
Problems occur when a second generation GPRS node (2G-GSN) attempts to interact with a third generation UMTS node (3G-GSN) because the 2G-GSN nodes and the 3G-GSN nodes support different kinds of protocols. As shown in FIG. 4, the GTP used for communication between 2G-GSN nodes tunnels both user and control data, while the GTP-C used for communicating between 3G-GSN servers tunnels only control data, and the GTP-U used for communicating between 3G-GSN gateways tunnels only user data. There is no protocol by which the 2G-GSN can communicate with a 3G-GSN server or a 3G-GSN gateway. Also, the GTP can only address one node, whereas the 3G-GSN Server and 3G-GSN Gateway are placed in two different nodes.
Currently, there is no provision permitting a 2G-GSN node to interact with the 3G-GSN server or a 3G-GSN gateway.
Thus, there is a need for a technique permitting 2G-GSNs to interact with 3G-GSN servers and 3G-GSN gateways to permit roaming between GPRS and UMTS networks.